Catch-22 is the catch-all term for a no-win situation that is a major theme and the coined catch-phrase that Joseph Heller uses to title his classic anti-war novel (and my favorite of all American novels, BTW). The phrase "catch-22" became a part of American terminology shortly after its use in the novel. Catch-22 is used often in the book and always when there is a conflict that is best solved with contradictory military logic. One example of the Catch-22 rule is the military edict created that disallows anyone from avoiding combat missions. Whenever an airman nears the mandatory maximum number of missions, the number is raised. Why? "Catch-22."
"That's some catch, that Catch-22," Yossarian observed.
"It's the best there is," Doc Daneeka agreed.
Another example occurs when military police enforce Catch-22. The MP explains that someone enforcing Catch-22 does not have to explain the rule to the accused. Catch-22
"... says they have a right to do anything we can't stop them from doing."
Yet another example deals with another of the novel's primary themes--sanity vs. insanity. Catch-22 also states that if an airman asks to get out of duty because he's "crazy," then he must not be "crazy."
"Sure, I can ground Orr, who is considered crazy, but first he has to ask me to."
"That's all he has to do to be grounded?"
"That's all. Let him ask me."
"And then you can ground him?" Yossarian asked.
"No. Then I can't ground him."
"You mean there's a catch?"
"Sure there's a catch," Doc Daneeka replied. "Catch-22. Anyone who wants to get out of combat duty isn't really crazy."
Yossarian, of course, does not believe there is a Catch-22, but because it is such an ever-changing rule that does not appear to be written anywhere, he has no way of proving it.